The Kinetic Sunyaev‐Zel’dovich Effect from Reionization

During the epoch of reionization, local variations in the ionized fraction(patchiness) imprint arcminute-scale temperature anisotropies in the CMBthrough the kinetic Sunyaev-Zel'dovich (kSZ) effect. We employ an improvedversion of an analytic model of reionization devised in Furlanetto et al.(2004)to calculate the kSZ anisotropy from patchy reionization. This model usesextended Press-Schechter theory to determine the distribution and evolution ofHII bubbles and produces qualitatively similar reionization histories to thoseseen in recent numerical simulations. We find that the angular power spectrumof the kSZ anisotropies depends strongly on the size distribution of the HIIbubbles and on the duration of reionization. In addition, we show that upcomingmeasurements of the kSZ effect should be able to distinguish between severalpopular reionization scenarios. In particular, the amplitude of the patchypower spectrum for reionization scenarios in which the IGM is significantlyionized by Population III stars (or by mini-quasars/decaying particles) can belarger (or smaller) by over a factor of 3 than the amplitude in moretraditional reionization histories (with temperature anisotropies that rangebetween 0.5 and 3 micro-Kelvin at l = 5000). We highlight the differences inthe kSZ signal between many possible reionization morphologies and discuss theconstraints that future observations of the kSZ will place on this epoch.Comment: 14 pages, 10 figures. Accepted for publication in Ap